1. Field of the Invention
The present invention relates to technology for obtaining information forming a basis for identifying constituent parts of a person in a moving image.
2. Description of the Related Art
There exists technology for determining the motion of moving images in which the subject is a person performing sign language, or the like. For example, Japanese Patent Application Publication No. 2002-165222 discloses that, as motion is performed, depending on whether the differential between a previous frame image and a current frame image is equal to or greater than a prescribed threshold value, serial processing is carried out to divide the whole image which constitutes a freely changeable window with a movable perimeter into small rectangular-shaped blocks, by demarcating an object having the next rank of importance after the main subject. Using the motion vectors which accompany the moving images of the blocks, the position and region of the movable-perimeter window for the next frame is estimated, and the movable-perimeter window is made to follow this motion, within its potential range of change.
Japanese Patent Application Publication No. 2004-303014 discloses that a captured image analyzing device extracts skin color regions of a subject person located in a captured image, from the image captured by a reference camera (captured image). More specifically, the RGB (red, green and blue) values of all of the pixels in the captured image are converted into values in the HLS (hue, luminosity and saturation) space, and pixels having values for the hue, luminosity and saturation within previously established threshold values are extracted as skin color regions. An outline extraction device extracts the outline of the subject person. A gesture recognition device then determines the facial position and the finger tip positions of the subject person in the actual space, on the basis of the outline information and skin color region information relating to the subject person.
In the technology in Japanese Patent Application Publication No. 2002-165222, since the positions of the hands are estimated by means of the motion vectors, the motion of an object that is unrelated to the subject person may be followed mistakenly. Furthermore, the skin color of people varies between different individuals, and therefore, it is not necessarily possible always to accurately determine the skin color of subject's hands within a universal skin color threshold value range as in the technology described in Japanese Patent Application Publication No. 2004-303014.